Characterising the mechanism of airway smooth muscle β2 adrenoceptor desensitization by rhinovirus infected bronchial epithelial cells

PLoS One. 2013;8(2):e56058. doi: 10.1371/journal.pone.0056058. Epub 2013 Feb 15.

Abstract

Rhinovirus (RV) infections account for approximately two thirds of all virus-induced asthma exacerbations and often result in an impaired response to β2 agonist therapy. Using an in vitro model of RV infection, we investigated the mechanisms underlying RV-induced β2 adrenoceptor desensitization in primary human airway smooth muscle cells (ASMC). RV infection of primary human bronchial epithelial cells (HBEC) for 24 hours produced conditioned medium that caused β2 adrenoceptor desensitization on ASMCs without an effect on ASMCs viability. Less than 3 kDa size fractionation together with trypsin digestion of RV-induced conditioned medium did not prevent β2 adrenoceptor desensitization, suggesting it could potentially be mediated by a small peptide or lipid. RV infection of BECs, ASMCs and fibroblasts produced prostaglandins, of which PGE2, PGF2α and PGI2 had the ability to cause β2 adrenoceptor desensitization on ASMCs. RV-induced conditioned medium from HBECs depleted of PGE2 did not prevent ASMC β2 adrenoceptor desensitization; however this medium induced PGE2 from ASMCs, suggesting that autocrine prostaglandin production may be responsible. Using inhibitors of cyclooxygenase and prostaglandin receptor antagonists, we found that β2 adrenoceptor desensitization was mediated through ASMC derived COX-2 induced prostaglandins. Since ASMC prostaglandin production is unlikely to be caused by RV-induced epithelial derived proteins or lipids we next investigated activation of toll-like receptors (TLR) by viral RNA. The combination of TLR agonists poly I:C and imiquimod induced PGE2 and β2 adrenoceptor desensitization on ASMC as did the RNA extracted from RV-induced conditioned medium. Viral RNA but not epithelial RNA caused β2 adrenoceptor desensitization confirming that viral RNA and not endogenous human RNA was responsible. It was deduced that the mechanism by which β2 adrenoceptor desensitization occurs was by pattern recognition receptor activation of COX-2 induced prostaglandins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Bronchi / cytology
  • Bronchi / immunology
  • Bronchi / virology*
  • Cells, Cultured
  • Culture Media, Conditioned / analysis
  • Epithelial Cells / immunology
  • Epithelial Cells / virology*
  • Female
  • Host-Pathogen Interactions*
  • Humans
  • Male
  • Middle Aged
  • Myocytes, Smooth Muscle / immunology
  • Myocytes, Smooth Muscle / virology*
  • Picornaviridae Infections / immunology*
  • Picornaviridae Infections / virology
  • Prostaglandins / immunology
  • RNA / analysis
  • Receptors, Adrenergic, beta-2 / immunology*
  • Receptors, Prostaglandin / antagonists & inhibitors
  • Rhinovirus / physiology*
  • Toll-Like Receptors / agonists
  • Toll-Like Receptors / immunology
  • Young Adult

Substances

  • Culture Media, Conditioned
  • Prostaglandins
  • Receptors, Adrenergic, beta-2
  • Receptors, Prostaglandin
  • Toll-Like Receptors
  • RNA

Grant support

JKB is supported by a National Health and Medical Research Council Career Development Fellowship #1032695. JLB is supported by a National Health and Medical Research Council Senior Principal Research Fellowship #571098. BGGO is supported by a National Health and Medical Research Council Career Development Fellowship APP1026880. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.